Method of and apparatus for testing materials



E: I I L 3 I I RN W V INVENTOR \NQ kw BR F. W. SPERR! JR. METHOD or AND.APPA RATUS FOR TESTING'MATERIALS. ORIGINAL FILED JULY 24 191B- EREDERICK "4V. 31%., GE PITTSBURGH, PENNSYLVANIA, ASSIGNOB TU THE KOPPERS COECCPAIIY,OF PITTSBURGH, PENNSYLVANIA, A GORPOBATIQN OF BENN- SYLVAITIA.

IvlETI-IOD OF AND APPAMELATUS FOR TESTING BEATERIALS.

Original application filed July 9.4, 1918, Serial No. 246,599. Divided and this application filed August 3.2,

To all whom it may concern Be it known that I, FnLonnroK TV. Srnnn, Jr., a citizen oi"- the United States residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, iormerlyresiding at @akmont, in the same county and State, have invented a new and useful im- 'provement in a Method of and Apparatus for Testing Materials, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming part o't this specification, in which Figures I and II are diagrammatic views embodying my invention, and

Figure III is a similar view showing a modification.

This is a division of my co-pending application, Serial No. 246,599,- filed July 24:, 1918. i

This invention relates to a method for testing the behavior of substances on heating and also to apparatus that l have developed to carry out this method. The method and apparatus have been more particularly designed for the testing of coal, the behavior of which at high temperatures is of great importance in the arts; and in the ensuing description I have usually referred to coal .as the substance to be tested, but it is to be understood that the method may also be applied to a wide variety of other materials. My method ofi'ers a means of determining all or any of the following important characteristics of material.

1. The rate ot'volume change under progressive heating and the total volume change after heating.

2. The pressure developed by the material when heated in a confined space.

3. The character of the product formed after subjecting the material to progressive heating at various rates.

4i. The nature and quality oi? any byproduct formed by progressive heating of the material.

lt may readily be seen that such information is of importance in relation. to a wide range o t-material.

. In the case oi coal, it is often desirable to determine, upon asmall scale, the quality of the residue left after heating the coal to 'a given temperature. This is of particular oven tle temperature will be occupying the space E.

ably pulverized to approximately 20 mesh Serial No. 581,417.

interest in connection with the investigation of coking coals, since the quality of the coke made from such coal is of very great industrial importance. liloreover, certain coals expand during the. coking process, while others contract. In the case of coals which expand, it is necessary to be able to determine the amount of pressure developed when the coals are coked in a confined space. The behavior coal upon. heating, the nature on"; the coke and byproducts, the amount of e1:- pansion or contraction, and the pressuredeveloped durln coking are profoundly ailected by such factors as the rate of heating, total-time of heating and temperature.

in the industrial coking of coal, it has been proven by number of different investigators that the heat penetration proceeds in such a way that the Zone oi high temperature in which the coking has taken place is always marked by rather sharply defined limits. W hen the coking has advanced, say,

four inches from the wall of the oven, the temperature at that point will be quite 'highposs1bly over 800 (3.,

while two inches Further in toward the center of the several hundred degrees lower. Some of the most important features of the coking process P pearto be related to this manneroi heat penetration, and ii satisfactory results on small scale tests are expecsed, this condition must be imitated as. closely as possible. This is what is accomplished by my method. One term of apparatus that l have used is shown 1n diagrammatic form in Figure I.

In the tube A is nlaced a sample of coal,

The coal is pretersize, although other degrees of fineness n'iay be used. is. weighed quantity oi coal is always used. The sample is held in place by the plugs (l and C. Plug C is preferably tired so as to prevent expansimi ot' the coal. toward the cold end oi the tube while plug is movable. 191.11g (I, however, might be made removable to facilitate the insertion and removal the test material. The tube A isfpreterably made of fused quartz although other reiractory material, such as glass, porcelain, or iron may be used. Quartz is preferred on account of its refractory quality and flow coeiiicient of expansion.

The tube A is supported at one end by the support J, while the other end rests upon the furnace D. The source of heating is the electric furnace D, which over the tube and has a tubular heating chamber, the length of which is preferably somewhat greater than the length of the sample and than the length of the section B occupied by the sample. The furnace I) may also be heated by gas, although an electric furnace is preferable. The furnace D is mounted on a carriage E, which runs over the track F. A point-er G attached to the carriage indicates upon the scale II the exact position of the end of the heating chamberof the furnace with respect to the end of the section occupied by the coal sample.

When testing coal, I weigh out such a sample that the space B is approximately 9 inches long, corresponding to the distance fromthe wall to the center of the usual byproduct coke oven.

In its simplest form, the test consists in moving the furnace D slowly in the direction of the arrow I until the furnace covers all of the section B. The tube is then removed from its support and from the furnace and the residuein section P taken out for examination. In the case of a' good coking coal, this residue consists of a heat cylinder oficoke. The total expansion or contraction that has taken place in the coking operation may be obtained by measuring the length of this cylinder. Various rates of coking may be imitated by moving the furnace faster or slower, always timing the progress of heating with reference to the position of the pointer G on the scale H. Various temperatures of coking may be tested by varying the temperature of the furnace D.

The laws of physics show that the time required for the flow of heat through a solid mass, one face of which is being heated, or in other words, the time required to effect a predetermined increase of temperature, is proportional to the square of the distance from the-heated face. Certain investigations show that this law is approximately applicable to the progress of heating in the coking of coal. In order to make the small scale tests comparable with actual practice, it is desirable to conform to this law of heating which may be readily done with my apparatus. I have found it preferable to advance the furnace over the section B at a rate in which-the distance traveled is a functionof the square root of the time. For example, suppose the total section 9 inches long-is to be heated in four hours, then according to the square root rule, one-half of the9'1nches would'be. traversed in the first hour. 7 /1 .2 -9" in the first two hours, the

/S/ IX 9 inthe first three hours, etc. Ihave adopted the practice of making heating curves corresponding to each rate of heating and these are followed by moving the apparatus by hand, but an apparatus may also be used in which the motion ismade automatic by clock Work or otherwise.

In the simplest method of testing, it is not absolutely essential to the principle of the method to use the plugs C and C, although better results are obtained by using these plugs.

lVhen it is desired to determine the expansion or contraction of the sample at various stages of heating, a light rod K is placed with one end in contact with the removable plug C, the other end operating against a pointer L suspended in such a way as. to indicate the movements of the plug on the scale M. The apparatus may be arranged so that the weight of the pointer is sufficient to keep the rod K incontact with the plug through any contraction that take place, but other means may be used to this Here, for sake of simplicity, the tube is shown without supports or furnace. The rod 0 which is preferably made of silica and is stronger than the rod K,'shown in Figure I, is held firmly in contact with the plug G and rests upon the support N. By a suitable arrangement of levers P P, the pressure developed is transmitted to the pan of a balance Q which is of a type requiring a very small degree of movement to indicate a given pressure. Balances may be obtained in which the required movement is less than inc-h. For this purpose, I prefer to use a platform scale, such for instance, as that defined in the Bureau of Standards Bulletin, issued May 1915, entitled Tolerances and specifications for weights and measures and weighing and measuring devices. The specific form of scale adapted for this purpose is one manufactured by the Toledo Scale Company, of Toledo, Ohio, and known as Scale No. 641.

IVhile I have illustrated in'FiguresI and II a formof my invention in which. the tube is stationary and the furnace stationary, I may use a stationary furnace and move the tube therethrough. This modification of my invention is shown in Figure III, lawman the corresponding parts have been given the. same reference numerals as in Figures I and II, but with the affix applied'tlie'rget o. In this fivure, I have also indicated more mechanically the character of the indicator Which maybe employed in indicating the extent of the expansion or contraction of it is desired simply to ascertain the character of the product resulting from heating, both plugs U C may be held in fixed relation to each other. Various other changes can be made in the details of construction and arrangement of the parts Without departing from the spirit and scope of my invention as defined in the claims.

The words tube and tubular as used herein and in the claims with respect to the container employed are to be broadly construed as covering any container of suitable character in which a test sample can be confined and treated as described.

I claim:

1. Apparatus for testing materials, comprising a refractory container and a heating furnace, the furnace and container being progressively movable relatively to each other, together with means actuated by the pressure generated in the container for indicating such pressure.

2. Apparatus for testing the pressure developed by heating substances, comprising a refractory tube adapted to contain a sample of the substance, a movable plug fitting against the end of the sample, apparatus connected with said plug and operating on the principle of a balance to indicate or record the pressure developed, and a furnace adapted to heat the tube, said tube and furnace being so mounted as to permit relative motion so that the sample may be heated progressively from one end to the other.

Apparatus for testing the pressure developed by heating substances, comprising a refractory tube, adapted to contain a sample of the substance, plugs fitting against the ends of the sample, the plug nearest the source of heat being movable, and the opposite plug being fixed, and an apparatus operating on the principle of a balance connected with the movable plug and adapted to register the changes occurring in the sample by heating it, the tube and furnace being so mounted as to permit of relative motion so that the sample may be heated progressively from one end to the other.

4. The herein described method of testing the behavior of substances on heating, consisting in enclosing a sample of the substance in a refractory container and applying heat progressively from one end of the sample to the other by moving the two relatively to a heated zone, and measuring the pressure generated.

In testimony whereof I have hereunto set my hand.

FREDERICK W. SPERR, JR. 

